Speed regulating arrangement for internal combustion engines

ABSTRACT

A speed regulating arrangement for internal combustion engines in which an electrical pulse generator is coupled to the crankshaft of the engine and is operated in accordance with the engine speed. The pulse generator applies its output to an electronic speed regulating circuit which, in turn, operates an electromagnet having a rotatable armature. The throttle flap of the engine is coupled to the armature and positioned in accordance with the signal output from the electronic speed regulating circuit. The latter has a series circuit of a monostable stage, a low pass filter, a regulating stage and a power amplifier.

United States Patent .11

Klaiber et al.

[451 Apr. 2, 1974 SPEED REGULATING ARRANGEMENT FOR INTERNAL COMBUSTION ENGINES [75] Inventors: Erich Klaiber, Stuttgart; Hans Stiickle, Neckarweihingen; Helmut A Domann, Leonberg, all of Germany [73] Assignee: Robert Bosch GmbH, Stuttgart,

Germany [22] Filed: Nov. 11, 1971 [2]] Appl. No.: 197,814

[30] Foreign Application Priority Data Nov. l3, 1970 Germany 2055874 [52] US. Cl 123/102, 310/279, 335/229, 307/88.5 [51] Int. Cl. F02d 11/10 [58] Field of Search 123/102; 324/166; 317/5; 310/30, 279; 335/229 [56] References Cited UNITED STATES PATENTS 3,249,098 5/1966 Rosenberg 123/102 3,252,022 5/1966 Smith 317/5 X 3,207,950 9/1965 Smith..... ..Q 317/5 X 3,374,374 3/1968 Smith 317/5 X 3,258,094 6/1966 Zechnall et al 317/5 X 3,264,496 8/1966 Scholl 317/5 X 3,157,807 11/1964 Kimberly, Jr. 317/5 X 3,560,854 2/1971 Moss et a1 123/102 X 3,346,771 10/1967 Sutton 123/102 X 3,613,820 10/1971 Bozoian... 317/5 3,058,039 10/1962 Ray 335/279 3,221,191 11/1965 Cuches et a1. 335/279 2,364,656 12/1944 Price 335/279 Primary Examiner-Laurence M. Goodridgc Attorney, Agent, or Firm-Michael S. Striker [57] ABSTRACT A speed regulating arrangement for internal combustion engines in which an electrical pulse generator is coupled to the crankshaft of the engine and is operated in accordance with the engine speed. The pulse generator applies its output to an electronic speed regulating circuit which, in turn, operates an electromagnet having a rotatable armature. The throttle flap of the engine is coupled to the armature and positioned in accordance with the signal output from the electronic speed regulating circuit. The latter has a series circuit of a monostable stage, a low pass filter, a regulating stage and a power amplifier.

15 Claims, 7 Drawing Figures PATENTEDAPR 21914 SHEET 2 BF 3 a W/ I.

SPEED REGULATING ARRANGEMENT FOR INTERNAL COMBUSTION ENGINES BACKGROUND OF THE INVENTION The present invention relates to a speed regulating arrangement for an internal combustion engine used to drive a load. Examples of a load driven by the engine are water pumps, electrical generators, motorizedsaws for power saws, floor scrapers, etc. With such driven apparatus it is required that the speed of the internal combustion engine remain constant even though the load varies. Thus, the water pressure should be independent of the quantity flow rate of the pump, and

should remain constant. At the same time the output voltage of the generator should be independent of the magnitude of the current and the cutting speed of the power saw should be independent of the length of the cut and independent from the applied pressure. The floor scraper or ground digging apparatus should dig uniformly and independent of the depth of operation. Considerable further examples of this type are also possible.

Mechanical centrifugal regulators are known in the art for purposes of speed regulation. These centrifugal regulators are used to actuate the throttle flap of an internal combustion engine. The mechanical centrifugal regulators have three distinct disadvantages: one disadvantage is that they are relatively heavy and are therefore not adapted for portable power saws. The second disadvantage of the centrifugal regulator is that they have a large regulating time constant, and as a result, when the regulators are used in conjunction with electrical generators or water pumps, the electrical voltage or water pressure varies too much when the load varies rapidly. The third disadvantage resides on the basis that upon load variations, a proportional speed change is obtained. 2

SUMMARY OF THE INVENTION It is an object of the present invention to provide a speed regulating arrangment for internal combustion engines which avoid the foregoing disadvantages of the conventional devices in the form of mechanical centrifugal regulators.

Another object of the present invention is to provide an arrangement which is reliable in operation and may be readily fabricated.

A further object of the present invention is to provide an arrangement of the foregoing character which may be easily installed in internal combustion engines.

The objects of the present invention are achieved by providing a pulse generator connected to the crankshaft of the engine and synchronously driven in accordance with the speed of the engine. The output of the pulse generator is applied to an input of an electronic speed regulator which, in turn, operates an electromagnet with a rotatable armature. The rotatable armature positions the throttle flap of the engine. A particularly advantageous arrangement, in accordance with the present invention, is achieved when the electronic speed regulator has a series circuit consisting of a monostable multivibrator or monostable switching stage, a low pass filter, a regulating stage, and a power amplifier.

Mechanical centrifugal regulators have the characteristic of proportional regulators. As a result, the

speed can be adjusted at constant load, but the speed drops with increasing load. This disadvantage can be avoided through a further embodiment of the present invention by providing that the regulating stage be in the form of a PI regulator. Residual speed variations are not possible when the regulating characteristic has an integrating portion.

When the throttle flap is to be actuated electromechanically, it is necessary to provide a rotatable armature which has a substantially constant torque over a relatively large angle of rotation of approximately This feature is attained in a further embodiment of the present invention by providing that the rotatable armature is in the form of a segment armature which has rounded recesses for increasing the torque in the initial or end position of the armature.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a schematic diagram of an internal combustion engine with a speed regulating arrangement;

FIG. 2 is an elevational view of an electromagnet with rotatable armature;

FIG. 3 is a schematic diagram of the arrangement of core laminations for the electromagnet, when being stamped, in accordance with the present invention;

FIG. 4 is an enlarged sectional view of the electromagnet of FIG. 2 when using a circular armature;

FIG. 5 is an enlarged sectional view of a part of the electromagnet of FIG. 2 when using a segment armature;

FIG. 6 is a circuit diagram of the speed regulating arrangement and shows the electronic components and their interconnections; and

FIG. 7 is a circuit diagram of a correction applying stage used in conjunction with the circuitry of FIG. 6.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawing, FIG. I shows an internal combustion engine with a cylinder 12 and a crankshaft housing 13. The internal combustion engine drives a centrifugal pump 23, with an extension of its crankshaft 14. The centrifugal pump 23 is secured or mounted fixedly to the chassis l 1, similar to the internal combustion engine. The crankshaft housing 13, furthermore, carries an ignition generator 15 on the side of the housing 13 which is opposite to that facing the centrifugal pump 23. The ignition generator 15 supplies power to a spark plug 17, by way of a cable 18, and to an electronic regulator 24, through an interconnecting cable 25. The ignition generator 15 is penetrated by a second extension of the crankshaft 14. This extension has, at its end, a pulley 16 which can drive about for the purpose of turning over or starting the engine. Connected to the cylinder 12, furthermore, is an intake manifold or suction intake 21 a gas applying unit 19, a throttle flap and an air filter 22. The throttle flap is not shown in the drawing. This throttle flap becomes actuated through a rotatable armature magnet 20, which receives voltage from an electronic regulator 24, through the interconnecting cable 26.

The rotatable armature electromagnet 20 is shown without a housing, in FIG. 2. This electromagnet consists essentially of a U-shaped core 31 which carries two coils or windings 34 on the poles or arms of the core. A rotatable armature 36 is rotatable in cooperation with the arms of the core. The core 31, furthermore, is constructed of individual laminations assembled together and interconnected with each other through soldered joints. A welded joint can also be used for this purpose. Such soldered or welded joint is denoted by the reference numeral 32. Two mounting holes 33 are provided for mounting the electromagnet to the gas applying housing 19. The gas applying unit 19 may be in the form of, for example, the conventional carburetor. The arms of the core 31 have circularshaped recesses on their inner surfaces for the purpose of accommodating the armature 36. Directly above the circular recesses, the arms of the core 31 have further circular-shaped recesses 35, and inclined surfaces 42 lie directly below the recesses within which the rotatable armature 36 is movable. The recesses 35 and the inclined surfaces 42 serve the purpose of reducing the stray magnetic flux. As may be seen from FIG. 3, the core 31 is particularly well adapted for mass production. The core laminations 31, lie directly against each other when they are stamped, and only very small waste pieces 39 are incurred.

FIG. 4 shows a circular armature 36a which is rotatably mounted upon an axle 37 and is shown, in FIG. 4, in a position corresponding to its maximum angular rotation. This armature has two wedged-shaped recesses 38a. The exterior surfaces of the armature, which face the core poles, have the form of spiral-shaped curves with linearly increasing radius.

FIG. shows a segment armature 36b, also in its maximum possible angular position. The segment armature 36b has straight-lined bordering side surfaces 41, and circular-shaped bordering recesses 38b. The outer surfaces of the segment armature 36b, which face the core 31, have the shape of spirals with linearly increasing radius.

FIG. 6 shows the circuit arrangement of the electronic speed regulator 24. This circuit consists of a current supply stage 50, a pulse shaping stage 60, a monostable multivibrator 70, a low pass filter 80, a regulating or control signal generating stage 90 and a power amplifier 100. A generator winding 49 has a center tap connected to the minus voltage supply line 56. The other two end terminals of the winding 49 are connected respectively, through diodes 51 and 52, with the positive voltage supply line 55. For purposes of smoothing and filtering the DC voltage, a Zener diode 53 and capacitor 54 are connected across the positive voltage supply line 55 and the negative voltage supply line 56. The capacitor 54 connected in parallel with the Zener diode 53, is an electrolytic capacitor.

The pulse shaping stage 60 is connected to both end terminals of the generator winding 49, through the two diodes 61 and 62. The pulse shaping stage has a series circuit including a resistor 63, a differentiating capacitor 65, and a diode 67. From the junction between the resistor 63 and the capacitor 65, leads a resistor 64. A diode 66 is connected between the negative voltage 4 supply line 56 and the junction between the capacitor and the diode 67.

The monostable multivibrator 70 includes two transistors 71 and 72 having their emitters directly connected to the minus voltage supply line 56. The collectors of these two transistors lead, through respective resistors 73 and 74, to the positive voltage supply line 55. The collector of the first transistor 71 is capacitively coupled, through a capacitor 75 to the base of the second transistor 72. The collector of the second transistor 72 is galvanically connected, through a resistor 76, with the base of the first transistor 71. A resistor 77, furthermore, is connected between the base of the first transistor 71 and the minus voltage supply line 56. A resistor 78, on the other hand, is connected between the base of the transistor 72 and the positive voltage supply line 55.

The low pass filter is in the form of a series circuit of two resistors 81 and 82. An electrolytic capacitor 83 is connected between the negative voltage supply line 56, and the junction between these two resistors 81 and The regulating stage includes, as its active component, an operational amplifier 91. The negative input to the amplifier 91 is connected first to the output of the low pass filter 80, secondly to a terminal 98, and thirdly to an adjustable speed-selecting means, here a resistor 97, which has one terminal of its winding connected to the negative voltage supply line 56. The other or uninverted input to the operational amplifier 91, corresponding to the positive input, is connected to the junction of two resistors 94 and 95 forming a voltage divider. The output of the operational amplifier 91 is connected, through a resistor 96 with the positive voltage supply line 55. A series circuit, furthermore, including a capacitor 93 and adjustable resistor 92, is connected between the output of the amplifier 91 and the negative or inverted input of the amplifier.

The power amplifier or electromagnetic control means 100 contains a modified Darlington circuit with a transistor 101 and a power transistor 102. The emitters of the two transistors are each connected to one terminal of a resistor 104. The coil 34 of the rotatable armature electromagnet 20, is connected between the emitter of the power transistor 102, and the negative voltage supply line 56. The base of the transistor 101 is connected, through a resistor 103, to the output of the regulating stage 90.

FIG. 7 shows the circuit diagram of an error correcting stage which has its output connected to the terminal 98 of the regulating stage 90. At the input of the error correcting state is a current transformer 112. The 5 terminals 111 of the primary winding of this current transformer 112, are connected to the output of an electrical generator which is driven by the internal combustion engine. The secondary winding of the current transformer 112 is connected across a trimming potentiometer 113. A rectifying bridge of the Graetz design is connected between the sliding contact of the trimming potentiometer 113 and one terminal of the winding of this potentiometer. The positive output of the rectifying bridge 114 is connected to the negative voltage supply line 56. The negative output of the rectifying bridge 114, furthermore, is connected to an electrolytic capacitor 115, which is connected parallel with a resistor 116. The capacitor 115 and resistor 116 have each one terminal connected to the negative voltage Since the speed regulating arrangement, in accordance with the present invention is also to be used in smaller internal combustion engines which do not possess a light generator, a separate generator winding 49 is required, which is held within the ignition generator 15. In operation of the arrangement, in accordance with the present invention, the built-in magnetic ring and the ignition generator 15, induces, through its rotation, a voltage within the ignition winding as well as in the auxiliary generator winding 49. The ignition winding itself is not adapted to supply current for the speed regulating arrangement itself, because the form as well as the ignition instant of the ignition pulse would be influenced in a disadvantageous manner thereby.

The generator winding 49 supplies the voltage for the speed regulating arrangement, and at the same time, the control pulse for the monostable multivibrator 70. The generator winding 49 is thereby constructed so that it has a relatively high internal impedance. At the same time, the generator winding will provide, when not under load, an alternating voltage exceeding 100 volts. The voltage increases within a few milliseconds, after passing through zero, to the level of approximately volts, determined by the Zener diode 53. In view of the high internal impedance of the generator winding 49, no resistor is required in front of the Zener diode 53. As a result of the steep voltage rise after passing through zero, the voltage on the positive line 55 drops to zero only for a small portion of the period, upon omission of the capacitor 54. When using the capacitor 54, at the same time, a smaller capacitance for this component can be used, in contrast with the conventional smoothing circuit which would require large capacitance values for this component. It has been found advantageous to connect the center tap of the generator winding with the negative voltage supply line 56, and to actuate the monostable multivibrator 70 by the end terminals of this winding through respective diodes 61 and 62. With this arrangement, it is possible to attain double the frequency of the input pulses, and the low pass filter 80 can, thereby be designed for a higher limiting frequency. At the same time, the regulating time constants of the speed regulating arrangement can be reduced.

The pulse shaping stage 60 has the task of differentiating the output pulses of the generator winding 49, for the purpose of creating steeper control pulses or actuating pulses for the monostable multivibrator 70.

The output pulses of the generator winding 49 are not of sinusoidal form, since the magnet for the ignition generator is designed so that the steepest possible pulses result in the ignition winding. The two diodes 66 and 67 provide for the feature that only positive control pulses are applied the monostable multivibrator circuit 70. The negative pulses are short-circuited to the negative voltage supply line 56. The resistors 63 and 64 form a voltage divider for the output pulses of the generator winding 49.

A monostable multivibrator 70 produces, in the conventional manner, rectangular-shaped pulses of definite duration, from the output pulses of the generator winding 49. The pulse repetition frequency of these rectangular-shaped pulses is equal to the frequency of the input pulses. The low pass filter forms the time average of the output voltage of the monostable multivibrator 70, and provides thereby at its output a DC voltage which has a level proportional to the pulse repetition frequency of the monostable multivibrator 70.

At the output of the low pass filter 80, therefore, is a DC voltage which is proportional to the rotational speed of the internal combustion engine. The regulating stage has the task to compare this DC output voltage with an adjustable input voltage signal, and to increase the opening of the throttle flap with the aid of the rotatable armature magnet 20, when the speed is below the desired input speed. The reverse situation takes place, and the throttle flap opening is reduced when the desired input speed is exceeded. For the purpose of applying the desired input speed, an adjustable resistor 97 is provided in accordance with the examplary embodiment described above. This resistor 97 serves to load the output of the low pass filter 80. The throttle flap is increased in its opening, when the output voltage of the operational amplifier 91 becomes more positive. The input voltage of the negative or inverted input of this amplifier must, therefore, be below the input voltage of the positive input or non-inverting input of the amplifier. The negative or inverting input of the amplifier is lower for a predetermined or given output actual speed, when the resistor 97 has a lower set resistance. Accordingly, it-is possible to attain a higher desired speed by setting the resistor 97 to a lower resistance value. In another method for this arrangement, the desired input setting is carried out with the resistor 97 omitted. In place of the resistors 94 and furthermore, a potentiometer is provided. The desired input value can then be applied through the voltage on the non-inverting input or positive input of the amplifier.

Through the use of the resistor 92 and the capacitor 93, the operational amplifier 91 is in the form of a regulator which has a regulating characteristic determined through the resistor 92, and which has a proportional component of response. When the speed of the internal combustion engine increases and the output voltage of the low pass filter also increases thereby, then the throttle flap closes for as long as the desired input value is not changed. The capacitor 93 however, also serves to apply an integral component for the regulating characteristics, whereby variations in the speed are integrated and delayed before applying to the power amplifier 100. With this arrangement, overshoot of the speed is considerably reduced or avoided. In addition, it is possible to fully smooth out or compensate against speed variations resulting from load changes, in contrast to the action obtainable from centrifugal regulators.

In the regulating arrangement in accordance with the present invention, therefore, a DC voltage which is proportional to the speed of the engine is applied to the inverting input of a regulating amplifier which has its output voltage applied directly, without further inversion, to the coil 34 of the electromagnet with rotatable armature. In view of the proportional section of the regulating arrangement, the latter operates more rapidly than the conventional mechanical centrifugal regulators. When the engine is used for driving an electrical generator as in case of emergency situations, for example, it

is desirable to have rapid response of the regulating circuit relative to variations of the load. This feature can be attained with the aid of the arrangement of FIG. 7, through the use of an error correcting stage adapted to alternating current generators. The current converter 1 12 provides a DC voltage having a magnitude proportional to the intensity of the current in the primary winding. This DC voltage is supplied through the rectifying bridge 114 and filter 115, 116, to the capacitor. When the current intensity varies rapidly in the positive direction, then the differentiating capacitor 117 transmits a negative voltage pulse to the terminal 98, and thereby to the inverting input of the operational amplifier 91. As a result, the throttle flap is rapidly increased in opening, through the coil 34. With the use of three phase generators, it is possible to introduce a separate correction into each phase, and to sum the voltage pulses at the terminal 98.

When the internal combustion engine is used for driving a DC generator, it is possible to save or omit the rectifying bridge 114, and the filter 115,116. This results from the condition that the current converter 112 is then self-differentiated and provides an output only upon variation of the current.

The functional operation of the rotatable armature shown in FIGS. 2 to 5, is based on the condition that the width of the air gap between the rotatable armature and the core is dependent upon the angle of rotation, or the position of the rotatable armature. Another condition is that the outer border or surface of the rotatable armature is not of circular shape, but is instead of spiral shape. For actuating a throttle flap, it is essential that the rotatable armature provides a constant torque over a relatively large rotational angle, as approximately 90, at constant magnetic field intensity, for resetting the rotatable armature a spring with linear spring characteristics is used, and as a result a linear increase in the rotational angle is achieved as a function of control current. The torque is to maintain its maximum value of its entire rotatable or positionable region of the armature. In order to attain a steep rise of torque characteristics upon rotation of the armature, the stray magnetic flux must be retained as small as possible. For this purpose, the recesses 38a in the circular armature 38b in the segment armature as well as the recesses 35 and 42 of the core cooperate with the respective recessees as may be seen in FIG. 2. The circular armature in accordance with FIG. 4, has, for example, a maximum rotational angle of 120 for a core width of 60. By further reducing the core width, even larger rotational angles are possible. The segment armature of FIG. 5, thereby makes it possible that a rotational angle of 90 is realized for a core width which is also 90. The advantage of the segment armature resides in the condition that for equal magnetic field intensity, the torque is greater. The advantage of a segment armature is also based on the condition that in view of the straight lined surfaces 41 the initial torque rises rapidly at smaller rotational angles, than in the circular armature. In general, threfore, the segment armature is better adapted for rotational angles up to 90.

As described in the foregoing, all requirements are fulfilled through the combination of the circuit of FIG. 6 in conjunction with the rotational armature illustrated in FIGS. 2 to 5. Regulation of the speed of an internal combustion engine is made possible, in accordance with the present invention through essentially more rapid response than is possible with conventional mechanical centrifugal regulators. Furthermore, the present invention provides a significantly greater regulating precision than the conventional devices. The failure rate in operation of the present invention is also less than in conventional devices, since mechanical centrifugal regulators have an essentially higher frictional effect than is applicable to the corresponding electronic arrangement.

When the internal combustion engine has a light generator and an arrangement for battery ignition, or when the engine is used for driving an alternating current generator, the input circuitry of the electronic speed regulator 24 is modified accordingly: no generator winding 49 for producing a supply voltage is then required. The supply voltage can, instead be more directly obtained from the light generator or from the output of the alternating current generator. Under these conditions, it is also no longer necessary to provide the generator winding 49 as a pulse generator. The input pulses for the monostable multivibrator can, in this case, be obtained through a switching contact in the ignition arrangement for the-engine. The output voltage from the alternating current generator driven by the engine can also be just as well coupled to the pulse shaping stage 60, through the diodes 61 and 62.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of speed regulators for internal combustion engines, differing from the types described above.

While the invention has been illustrated and described as embodied in speed regulators for internal combustion engines, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.

We claim:

1. An arrangement for regulating the speed of an internal combustion engine having a throttle valve, comprising, in combination, speed-selecting means for selecting a speed for the engine; speed-monitoring means for determining the actual speed of the engine; controlsignal generating means provided with input means connected to both said speed-selecting means and said speed-monitoring means and having an output, and operative for generating at said output a control signal comprised of a first signal component proportional to the difference between the selected speed and the actual speed and a second signal component proportional to the time integral of said difference; and electromagnetic control means coupled to said throttle valve and having a control input connected to the output of said control-signal generating means for receiving said control signal and operative for controlling the position of steady-value D.C.

9 7 said throttle valve in dependence upon said control signal wherein both said speed-selecting means and said speed-monitoring means have an electrical output, and wherein said control-signal generating means comprises an operational amplifier provided with input means connected to the electrical output of said speedselecting means and of said speed-monitoring means, and wherein said operational amplifier has an output connected to said control input for applying the output signal of said operational amplifier to said control input, and wherein said operational amplifier further includes a feedback network connected between the output of said operational amplifier and said input means thereof, said feedback network comprising a resistor and a capacitor connected in series so as to establish a proportional-plus-integral transfer function for said operational amplifier.

2. An arrangement for regulating the speed of an internal combustion engine having a throttle valve, comprising, in combination, speed-selecting means for selecting a speed for the engine; speed-monitoring means for determining the actual speed of the engine; controlsignal generating means provided with input means connected to both said speed-selecting means and said speed-monitoring means and having an output, and operative for generating at said output a control signal comprised of a first signal component proportional to the difference between the selected speed and the actual speed and a second signal component proportional to the time. integral of said difference; and electromagnetic control means coupled to said throttle valve and having a control input connected to the output of said control-signal generating means for receiving said control signal and operative for controlling the position of said throttle valve in dependence upon said control signal; and further comprising additional means connected to said control input and connectable to an electrical generator driven by the engine and operative for applying to said control input an electrical signal in response to a change in the output of such electrical generator for causing said control means to vary the position of said throttle valve in a direction counteracting such change.

3. An arrangement as defined in claim 1, wherein said speed-monitoring means comprises pulse generating means synchronized with engine rotation and operative for generating a train of pulses whose pulserepetition frequency is proportional to engine speed, and means for converting said train of pulses into a steady-value DC. voltage proportional to engine speed.

4. An arrangement as defined in claim 3, wherein said means for converting comprises a monostable multi-vibrator having an input connected to said pulsegenerating means and operative for generating in response to each of said pulses a pulse of predetermined duration, and low-pass filter means connected to said monostable multi-vibrator to receive said pulses of predetermined duration and operative for generating said voltage proportional to engine speed.

5. An arrangement as defined in claim 1 wherein said control-signal generating means comprises means for generating a continuously variable control signal whose value varies continuously in response to changes in said difference.

6. An arrangement as defined in claim 1, wherein said control-signal generating means comprises means for generating a control signal composed of a first signal component proportional to the difference between the selected speed and the actual speed and a second signal component proportional to the time integral of said difference.

7. An arrangement as defined in claim 3, said engine including an ignition arrangement of the type including a rotating magnet arrangement synchronized with engine rotation, and wherein said pulse-generating means comprises a winding so located with respect to said magnet arrangement that rotation of said magnet arrangement induces voltage pulses in said winding.

8. An arrangement as defined in claim 3, said engine including an ignition arrangement of the type including an interruptor switch synchronized with engine rotation, said interruptor switch constituting said pulsegenerating means.

9. An arrangement as defined in claim 3, wherein said pulse-generating means comprises an AC. current generator mechanically coupled to the engine so as to be driven in synchronism with engine rotation.

10. An arrangement as defined in claim 3, wherein said control means includes an electromagnet so coupled to said throttle valve as to vary the position of said throttle valve in dependence upon the extent of energization of said electromagnet, and a power amplifier having an output connected to said electromagnet to furnish energizing current to the latter and having an input constituting said control input and connected to said output of said operational amplifier.

11. An arrangement as defined in claim 4, wherein said speed-monitoring means further includes pulseshaping means connected between the output of said pulse-generating means and the input of said monostable multivibrator.

12. An arrangement as defined in claim 11, wherein said pulse-shaping means comprises differentiating capacitor means operative for differentiating said train of pulses and applying the resulting pulses to said input of said monostable multivibrator.

13. An arrangement as defined in claim 2, wherein said additional means comprises a current transformer having a secondary winding connected to said control input and having a primary winding connectable in the current path of such electrical generator.

14. An arrangement as defined in claim 3, wherein said pulse-generating means comprises winding means and means for generating voltage pulses across said winding means in synchronism with engine rotation, and means connecting said winding means to said operational amplifier for applying to the latter biasing voltage derived from the voltages generated across said winding means.

15. An arrangement as defined in claim 14, and further including a Zener diode connected across said winding means and also a capacitor connected across said winding means, for smoothing the biasing voltage applied to said operational amplifier. 

1. An arrangement for regulating the speed of an internal combustion engine having a throttle valve, comprising, in combination, speed-selecting means for selecting a speed for the engine; speed-monitoring means for determining the actual speed of the engine; control-signal generating means provided with input means connected to both said speed-selecting means and said speed-monitoring means and having an output, and operative for generating at said output a control signal comprised of a first signal component proportional to the difference between the selected speed and the actual speed and a second signal component proportional to the time integral of said difference; and electromagnetic control means coupled to said throttle valve and having a control input connected to the output of said controlsignal generating means for receiving said control signal and operative for controlling the position of said throttle valve in dependence upon said control signal wherein both said speedselecting means and said speed-monitoring means have an electrical output, and wherein said control-signal generating means comprises an operational amplifier provided with input means connected to the electrical output of said speed-selecting means and of said speed-monitoring means, and wherein said operational amplifier has an output connected to said control input for applying the output signal of said operational amplifier to said control input, and wherein said operational amplifier further includes a feedback network connected between the output of said operational amplifier and said input means thereof, said feedback network comprising a resistor and a capacitor connected in series so as to establish a proportionalplus-integral transfer function for said operational amplifier.
 2. An arrangement for regulating the speed of an internal combustion engine having a throttle valve, comprising, in combination, speed-selecting means for selecting a speed for the engine; speed-monitoring means for determining the actual speed of the engine; control-signal generating means provided with input means connected to both said speed-selecting means and said speed-monitoring means and having an output, and operative for generating at said output a control signal comprised of a first signal component proportional to the difference between the selected speed and the actual speed and a second signal component proportional to the time integral of said difference; and electromagnetic control means coupled to said throttle valve and having a control input connected to the output of said control-signal generating means for receiving said control signal and operative for controlling the position of said throttle valve in dependence upon said control signal; and further comprising additional means connected to said control input and connectable to an electrical generator driven by the engine and operative for applying to said control input an electrical signal in response to a change in the output of such electrical generator for causing said control means to vary the position of said throttle valve in a direction counteracting such change.
 3. An arrangement as defined in claim 1, wherein said speed-monitoring means comprises pulse generating means synchronized with engine rotation and operative for generating a train of pulses whose pulse-repetition frequency is proportional to engine speed, and means for converting said train of pulses into a steady-value D.C. voltage proportional to engine speed.
 4. An arrangement as defined in claim 3, wherein said means for converting comprises a monostable multi-vibrator having an input connected to said pulse-generating means and operative fOr generating in response to each of said pulses a pulse of predetermined duration, and low-pass filter means connected to said monostable multi-vibrator to receive said pulses of predetermined duration and operative for generating said steady-value D.C. voltage proportional to engine speed.
 5. An arrangement as defined in claim 1 wherein said control-signal generating means comprises means for generating a continuously variable control signal whose value varies continuously in response to changes in said difference.
 6. An arrangement as defined in claim 1, wherein said control-signal generating means comprises means for generating a control signal composed of a first signal component proportional to the difference between the selected speed and the actual speed and a second signal component proportional to the time integral of said difference.
 7. An arrangement as defined in claim 3, said engine including an ignition arrangement of the type including a rotating magnet arrangement synchronized with engine rotation, and wherein said pulse-generating means comprises a winding so located with respect to said magnet arrangement that rotation of said magnet arrangement induces voltage pulses in said winding.
 8. An arrangement as defined in claim 3, said engine including an ignition arrangement of the type including an interruptor switch synchronized with engine rotation, said interruptor switch constituting said pulse-generating means.
 9. An arrangement as defined in claim 3, wherein said pulse-generating means comprises an A.C. current generator mechanically coupled to the engine so as to be driven in synchronism with engine rotation.
 10. An arrangement as defined in claim 3, wherein said control means includes an electromagnet so coupled to said throttle valve as to vary the position of said throttle valve in dependence upon the extent of energization of said electromagnet, and a power amplifier having an output connected to said electromagnet to furnish energizing current to the latter and having an input constituting said control input and connected to said output of said operational amplifier.
 11. An arrangement as defined in claim 4, wherein said speed-monitoring means further includes pulse-shaping means connected between the output of said pulse-generating means and the input of said monostable multivibrator.
 12. An arrangement as defined in claim 11, wherein said pulse-shaping means comprises differentiating capacitor means operative for differentiating said train of pulses and applying the resulting pulses to said input of said monostable multivibrator.
 13. An arrangement as defined in claim 2, wherein said additional means comprises a current transformer having a secondary winding connected to said control input and having a primary winding connectable in the current path of such electrical generator.
 14. An arrangement as defined in claim 3, wherein said pulse-generating means comprises winding means and means for generating voltage pulses across said winding means in synchronism with engine rotation, and means connecting said winding means to said operational amplifier for applying to the latter biasing voltage derived from the voltages generated across said winding means.
 15. An arrangement as defined in claim 14, and further including a Zener diode connected across said winding means and also a capacitor connected across said winding means, for smoothing the biasing voltage applied to said operational amplifier. 